Celery refers to the green, stalky plant we are most familiar with here in the US, while Celeriac is grown for the absolutely delicious bulbous growth at the root. Celery is best started indoors 10-12 weeks before transplanting (it is slow to germinate). Celery is a heavy feeder and requires a rich soil and constant moisture for best performance. Plant 1/8 inch deep in warm soil (65-70 F), and do not expose seedlings or plants to temperatures below 50-55, as this will induce bolting. Once nighttime temperatures are warm, transplant into rich soil and keep well feed and moist.